Determination of salmeterol, α-hydroxysalmeterol and fluticasone propionate in human urine and plasma for doping control using UHPLC-QTOF-MS.

Salmeterol and fluticasone are included in the Prohibited List annually issued by the World Anti-Doping Agency. While for other permitted beta-2 agonists a threshold has been established, above which any finding constitutes an Adverse Analytical Finding, this is not the case with salmeterol. The salmeterol metabolite, α-hydroxysalmeterol, has been described as a potentially more suitable biomarker for the misuse of inhaled salmeterol. In this study, a new and rapid UHPLC-QTOF-MS method was developed and validated for the simultaneous quantification of salmeterol, α-hydroxysalmeterol and fluticasone in human urine and plasma, which can be used for doping control. The analytes of interest were extracted by means of solid phase extraction and were separated on a Zorbax Eclipse Plus C18 column. Detection was performed in a quadrupole time-of-flight mass spectrometer equipped with an electrospray ionization source, in positive mode for the detection of salmeterol and its metabolite and in negative mode for the detection of fluticasone. Method was validated over a linear range from 0.10 to 2.00 ng/ml for salmeterol and fluticasone, and from 1.00 to 20.0 ng/ml for α-hydroxysalmeterol, in urine, whereas in plasma, the linear range was from 0.025 to 0.500 ng/ml for salmeterol and fluticasone, respectively.

Enantioselective disposition of (R)-salmeterol and (S)-salmeterol in urine following inhaled dosing and application to doping control.

Salmeterol (USAN, INN, BAN) is a long-acting beta2-adrenoceptor agonist (LABA) widely used in the treatment of airways disease. Although salmeterol is permitted via inhalation by athletes and supratherapeutic dosing may enhance performance, no urine threshold has been established by the World Anti-Doping Agency (WADA). Salmeterol is a chiral compound consisting of (R)- and (S)-enantiomers, normally administered as racemic (rac-) mixture via inhalation. Levels of rac-salmeterol in urine are often below detectable levels and there is surprisingly little information regarding the enantioselectivity of salmeterol pharmacokinetics. In this study, subjects inhaled either 50 (n = 6) or 200 µg (n = 4; generally regarded as maximum therapeutic dose) of salmeterol and urine was then collected for 24 h and analyzed by enantioselective ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Maximum rac-salmeterol urine concentrations were obtained at 2 h for both doses with medians of 0.084 ng/mL after the 50 µg dose and 2.1 ng/mL after the 200 µg dose, with an individual maximum of 5.7 ng/mL. Levels were detectable at 24 h for both doses. Salmeterol displayed enantioselective pharmacokinetics, with a mean ± SD log (S):(R) = 0.055 ± 0.025 (P < 0.0001) equivalent to (S):(R) of 1.13. In conclusion, rac-salmeterol by inhalation exhibits modest enantioselectivity in urine following single dose administration and can be detected following a single 50 µg dose for up to 24 h after inhalation. The present findings are of relevance if a urine threshold limit is to be introduced for salmeterol on the list of prohibited substances. The application of an enantiomer ratio analysis may offer improved discriminatory detection capability for doping control analysis applications. Copyright © 2016 John Wiley & Sons, Ltd.

Beta2-Agonist Doping Control and Optical Isomer Challenges.

The World Anti-Doping Agency (WADA) currently allows therapeutic use of the beta2-agonists salbutamol, formoterol and salmeterol when delivered via inhalation despite some evidence suggesting these anti-asthma drugs may be performance enhancing. Beta2-agonists are usually administered as 50:50 racemic mixtures of two enantiomers (non-superimposable mirror images), one of which demonstrates significant beta2-adrenoceptor-mediated bronchodilation while the other appears to have little or no pharmacological activity. For salbutamol and formoterol, urine thresholds have been adopted to limit supratherapeutic dosing and to discriminate between inhaled (permitted) and oral (prohibited) use. However, chiral switches have led to the availability of enantiopure (active enantiomer only) preparations of salbutamol and formoterol, which effectively doubles their urine thresholds and provides a means for athletes to take supratherapeutic doses for doping purposes. Given the availability of these enantiopure beta2-agonists, the analysis of these drugs using enantioselective assays should now become routine. For salmeterol, there is currently only a therapeutic dose threshold and adoption of a urinary threshold should be a high priority for doping control.